Abstract: A process for preparing a composite of two or more continuous phases, one which is tantalum carbide or a mixture of tantalum carbide and carbon which comprises(1) impregnating a preform of graphite or a similar material in the form of a porous block or woven fiber form with a reactive carbon source such as petroleum pitch, a coal tar pitch, a thermal setting resin, or a sugar;(2) pyrolyzing the reactive carbon source to form carbon;(3) impregnating the preform with either Ta(OCH.sub.3).sub.5 or Ta(OCH.sub.2 CH.sub.3).sub.5 under anhydrous conditions;(4) hydrating the Ta(OCH.sub.3).sub.5 or Ta(OCH.sub.2 CH.sub.3).sub.5 to precipitate Ta.sub.2 O.sub.5 throughout the preform; and(5) heating the preform at a temperature of 1400.degree. C. or more until the Ta.sub.2 O.sub.5 has reacted with the carbon to form tantalum carbide.

Abstract: The method of coating ceramic whiskers selected from the group consisting SiC, graphite, boron carbide and alumina with magnesium by sublimation and finally by magnesium oxide (MgO) after oxidation comprising(a) heating powdered Mg and SiC.sub.w mixture in an oxygen free atmosphere to a temperature of 400.degree. C. to 550.degree. C.(b) igniting the mixture in air in the presence of O.sub.2 (which may incidently cause the mixture to attain a temperature more than 1800.degree. C.) that the desired end results in a coating of MgO on the whisker or particle surfaces, to obtain novel coated whiskers varying in length from 10-100 microns.